Pollen-specific regulation of vacuolar H+-PPase expression by multiple cis-acting elements

We dissected the regulatory region of the AVP1 gene encoding the vacuolar H +-pyrophosphatase (V-PPase) of Arabidopsis thaliana by using a GUS-reporter assay system. The cloned 1.4 kb 5'-regulatory region in the GUS-reporter t ransgenic plants was sufficient for the light-induced repression. Furthermo re, the 1.4 kb regulatory region was active in all tissues examined and its activity was especially enhanced in pollen, whereas the shorter 0.4 kb reg ulatory region was active only in pollen. Further detailed analyses reveale d that the GUS activity in pollen was regulated by at least three cis-actin g regions in an additive or synergetic manner. These findings establish a d istinct mechanism of the tissue-specific regulation of V-PPase expression i n developing pollen, and imply the biological significance of the V-PPase i n pollen maturation.